Among environmental pollutants heavy metals make up a separate category: contrary to most organic contaminants heavy metals occur naturally, they are persistent, they bio-accumulate and are potentially toxic to man and biota. Metal toxicity can cause very diverse and sometimes baleful effects. Cadmium for example may cause renal dysfunction and respiratory problems in humans and animals. In plants growth retardation occurs as well as root damage, and noxious effects on physiological processes have been observed. Moreover, cadmium is a carcinogen.
Among heavy metals a distinction is made between essential and non-essential heavy metals. Essential metals such as copper, zinc and iron are essential for proper functioning of certain physiological processes, but are potentially toxic at supra-optimal concentrations. Non-essential metals such as cadmium and lead are not physiologically necessary and are generally toxic at lower concentrations.
During my PhD I will try to develop a set of biomarkers for metal toxicity and metal sensitivity in aquatic ecosystems by means of genome and proteome analyses of freshwater algae. Unicellular algae are at the base of the food chain in aquatic systems. Metal homeostatic mechanisms in these organisms therefore determine to a large extent bio-accumulation or concentration processes at higher levels in the food chain. Little mechanistic information on metal toxicity in these organisms is available. Insight into these mechanisms is however of crucial importance for the development of appropriate tools which allow for rapid detection of metal toxicity. In addition, unicellular algae are organisms which are suitable for high throughput screening. They are easily grown in a short time in a cheap way.
I am investigating the molecular biological effect of one essential (copper) and one non-essential (cadmium) metal in different species of freshwater algae (Chlamydomonas reinhardtii, Chlorella vulgaris and Aulacoseira granulata). Not only the effects of a one time exposure will be studied but mechanisms playing a role in acclimation/adaptation will be investigated, too. Practically this will be done by integrating genomic and proteomic data as well as data on bioavailability, uptake and elimination and physiological endpoints.
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